It was previously shown that aryl chlorodithioformates react with esters of trivalent phosphorus acids according to the following general equation (U.S. Pat. No. 3,089,891): ##STR3## The above primary product has two organophosphorus groups, one having phosphorus bonded to the carbon atom that was initially part of the thiocarbonyl group (C.dbd.S) and the other having phosphorus bonded to the sulfur atom that was initially part of the thiocarbonyl group. There are no bond rearrangements on the aryl group of the dithioformate during the reaction.